More than 500 people from a fringe Christian group who spread rumours about the world's impending end have been arrested in China.

In Qinghai province alone police held more than 400 members.

Officers seized leaflets, CDs, books and other apocalyptic materials across eight provinces and regions, from the prosperous east coast to less developed western China.

The detentions come ahead of Friday, December 21 - a date some say the Mayans prophesied would be the end of the world.

Those held are members of the group Almighty God, which is also called Eastern Lightning, after a phrase from the Bible's Book of Matthew. Widely regarded as a heretical Christian sect, the group preaches that Jesus has reappeared as a woman in central China. It has been accused of targeting Christians, kidnapping and beating them to force conversions.

Chinese society has been in tumult as decades of rapid free-market economic growth discredit communist ideology, loosen social controls and pull hundreds of millions from the countryside to the cities. Into the spiritual void have rushed traditional Buddhist groups and Daoist practices, as well as evangelical Christian churches and other spiritual groups, some with unorthodox and apocalyptic visions.

Eastern Lightning first appeared around 20 years ago, and the official Xinhua News Agency said that its members had "recently latched on to the Mayan doomsday prophesy to predict that the sun will not shine and electricity will not work for three days beginning on December 21."

A public notice on the web site of Qinghai provincial government said local police are waging a "severe crackdown" on the group described as a cult with "strong political penchants." The government urged the public to inform the police of any illegal propaganda, gathering and preaching by the group.